Numerous devices are on the market today to sense various conditions such as humidity and temperature. One of the more common forms of these sensing devices uses a coil of a spirally wound laminated sensing member in which one layer of the laminate is relatively insensitive to changes in the condition being sensed while another layer is sensitive to the condition being sensed. This sensitive layer changes in dimension in response to changes in the sensed condition. This causes the coil to move in a predictable manner in response to changes in the sensed condition. Thus, by fixing one end of the member and connecting the other end of the member to an appropriate mechanism, the movement of the coil can be used to drive a pointer and thus quantify the movement.
Most devices of this type provide a means to connect the circular movement of the coil to a pointer rotatable about the axis of the coil. The pointer then operates in a reading plane normal to the axis of the coil. One problem with such construction is that the interconnection between the coil and pointer is costly to produce and calibrate. This has resulted in the devices being manually assembled thereby subjecting the coil to contamination and damage. Further, the power to drive the pointer was difficult to obtain from the coil thereby reducing its accuracy and response time.